Telephone-transmitter



(No Model.)

-J. 8v H. M. GOODMAN. TELEPHONE TRANSMITTER.

Patented Dec. 4, 1894.

zfmmfd @and W Ilmmr l, ,I L x .M .f ,E www Illu. Ur .M A M. ...www yx f @/%vy m f i H UNITED STATES PATENT OFFICE.

JOHN GOODMAN AND HENRQI M. GOODMAN, OF LOUISVILLE, KENTUCKY.

TELEPHONE-TRAN'SMITTER.

SPECIFICATION forming part of Letters Patent No. 530,412, dated December 4, 1894. p Application tiled July 3, 1894. Serial No. 516,490. (No model.)

To all whom it may concern:

Be it known that we, JOHN GOODMAN and HENRY M. GOODMAN, citizens of the United States` and residents of Louisville, in the county of Jeerson and State `of-Kentucky,

have invented certain new and useful Im` provements in Telephone-Transmitters;" and we do declare the following to be a full, clear, and exact description of. the invention, such as will enable others skilled in the art to which it appertains to make and use the same,`refer`` Fig. 4 is a detail of elastic band connection of diaphragm and magnet. I n l Our-invention has relation to certain new` and usefulimprovoments in te1ephones,lall as hereinafter fully described and pointed out in theappended claims.

May 1, 1894, we have described certain forms of telephone transmitters, in which commi!` nuted magnetic material,`.between the opposite poles of two magnets, andconstituting a" part of thefelectric circuit wasthe essential agent in varying the4 strength of thecurrent."

We have discovered that the'number of magnets, or what is equivalent, the number' ofi magnetic elds, with included magneticlma-n terial in a comminuted state, may be multi-` plied with advantage in the same instrument. The mechanical devices by which this may be I accomplished are numerous, but we'willonlv describe such as we have `found by experience to be practically useful and suttlcientto illustrate the principle. i I Fig. 1 and 2 show the simplest form of the instrument. u i i In Fig; 1 B is the `front of the frame having an opening for the mouth piece corresponding with the diaphragm D and a base with a cavity for the accommodation of the` condenser G. S is a spring attached to some Fig. 2 is a partial sec` partof the 'support of the diaphragm and extending to the central portiomthereof upon which it rests by means of the projection X. This spring may be of steel and magnetized and a bar lof soft iron M affixed at right angles to its free extremity, which will representa pole of the magnet and the other magfnets must approach it with anopposite polarity; or `the spring may be of non-magnetic metal, and the bar a magnet, in which case'the opposingmagnets must present different poles on each side of the middle ofthe bar magnet. The comminuted magnetic material is represented at y. E is the support for the Inagnets represented by M, which magnets may vary in number and size as well as proximity or adjustment to M. The support E is provided with a foot F slidable in a groove in the base block G', the adjustment being madexby a screw rod K which engages `a threaded opening in said support, and has` a bearing at 0 in thelower front portion of `the case, being prevented from longitudinal ,movement by means of collars or shoulders.

I i .The projecting end of said rod may bepro- In Patents Nos. 433,505, dated April 10, 1894, and 498,019, dated May 22, 1894,`and in appli- `cations now. pending, Serial No.497,539, iiled January 20,1894, and Serial No. 509,686, filed vided with a head by means of which the rod may be turned, as in the ligure, or it may bey made angular to receive a key which may be removed j after adjustment has been made. Infadditionjto this general adjusting arrange- `ment,`each' magnet may have an individual adjusting appliance.` I is an induction coil which may be placed in any convenient situation `within or Without the case. Thisframe is designed to tit into a protecting caseand is toibe provided with suitable contacts for makingfconnections with battery and line circuits.

Fig. 2 is a horizontal sectional view showing the magnetic cross bar M attached at right angles to the springS and two adjustable magnets M.

\ Fig.3 is a more perfect form of the instruroo p S from a support above the diaphragm and impinging upon a projection Z from the center of thediaphragm through which .vibrations may be. imparted t0 it.M To this proies:

tion it is connected by an elastic band K to maintain absolute contact in the event of Violent jars. M and fm are the co-operating magnets the approximated poles of which are different above and below the center of the bar magnet so that they may present an opposite polarity to that portion ot' said bar magnet with which they correspond.

The adjustable magnets are sharp pointed while the magnetic surface which they approach is either plane or slightly concave. This, we have found to be the best relative shapes for the opposed magnetic electrodes. The linest cambric needle makes an excellent magnet for penetrating the magnetic material. The only objection to it is that such 'a slender magnet is a bad conductor, but this may be overcome by multiplying their number.

To appreciate the peculiarity of an instrument thus constructed it is necessary to understand the mode of action ot' iron filings, or its equivalent, in the magnetic eld as anagent in modifying the electric current as compared with the other substances in common use for that purpose. Take, forinstance, carbon as typical of a certain class. The conductivity of this is increased by pressure, owing to a change thereby effected in its ultimate or molecular constitution, analogous to 'a molecular change which occurs in selenium when exposed to sunlight. The etecting of this pressure necessarily implies resistance on the part of the material subjected to it, and if the pressure on the material is excessive its molecular integrity is destroyed and it is rendered useless. In the case under consideration the conditions are different. Here the magnetic particles are simply suspended in the magnetic field between the opposing magnetic electrodes in a granular, not molecular condition, each granule, no matter how small it may be, produced by mechanical means, consisting of an infinite number of molecules. These granules, of course, arrange themselves in the lines of magnetic force and constitute the channels of conduction for the electricity. When the electrodes approximate the lines of force and the chains of granules are straightened and the channels of conduction are shortened, againthe magnetic granular mass serves more or less under all circumstances as a conductor. When the magnetic electrodes are approximated the route of the current is shortened and its passage facilitated. ln this respect the action is similar to what takes place in a water rheostat or telephone transmitter, but diers materially from it in one respect--that in addition tothe approximation of the electrodes through a conducting medium, the vibratory magnet during approach brings along with it -innumerable small particles of the magnetic .materiaL which, coming in contact with the particles sustained by the stationary magnet-fgreatly,inc'g'reasey,the numbery .of 'channels ot conduction, theY reverse 4happenin g when said magnet recedes. Thus it must be admitted that at no timevis there any actual pressure exercised upon the granular mass and consequently lno obstacle offered to the free movement of the vibratory electrode bar or magnet. To accomplish fully the object designed the granular magnetic mass, at-

' tached to one electrode `must be large as compared with the size of the electrode which penetrates it. It should not be confined too strictly in a receptacle but its particles should be allowed space for free movement upon each other, the magnetic influence being sutticient ordinarilyto maintainthem'situj.

Nor is any envelope necessary to protect them from atmospheric influence when they are made of material not subject to change in the atmosphere. The points of the penetrating magnets may be of any form so that the liability of subjecting the granules to actual pressure is avoided. When this happens, a disagreeable, grating sound is heard when the diaphragm vibrates and a frying sound when it is at rest, from the simple passage of the current. A conical or wedge shaped point like the end of a chisel or the edge of a knife blade is preferable.

Returning to the construction ot the instrument it will be observed that the vibratory barV magnet is arranged upon the principle of the lever (Fig. 3) for which We make no claim per se at. present, as it' is fully set forth in one of our pending applications (Serial No. 509,686, filed May 1, 1894). The fulcrum or tixed point is at S and from this down the arc of movement increases until at the lower end the terminal magnet penetrates the mass with quite a plunge. The magnets near the fulcrum give high notes, more perfectly accentuated, and those near the lower end render the base notes loudest. The lowest magnet or magnets, as there may be more than one, facing a transverse bar as in Fig. 1, may be brought into play by a strong current, but ordinarily they only serve as safety valves in the event of an excessive discharge lsuch as may be experienced from currents induced by lightning, &c.

Of magnetic substances, for making the granular mass to be included between the magnetic electrodes, we have used iron, steel, nickel, cobalt, manganese, iron pyrites, oxide of iron, thin iron plates coated with silver copper, or gold, alloys of iron with copper, aluminum and manganese, and various combinations of them.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent, is-

1. In a telephonie instrument, the combination of a diaphragm, a vihratory magnet having contact with said diaphragm, a flexible or spring support for said magnet, a series of opposing magnets approximating said vibratory magnet and having their approxi ICO mated poles of opposite polarity to that of the part of the vibratory' magnet which they approximate, comminuted magnetic material interposed between the vibratory and the op` 3. In atelephonic instrument, the combination with a diaphragm, a spring-supported `Vibratorymagnet making contact with said diaphragm, a series of opposing electrodes approximating said Vibratory magnet at right angles and having their approximated poles of opposite polarity to that part of said vibratory magnet which each approximates, and a variable resistance of granular magnetic material between each opposing electrode and the vibratory magnet, substantially as speci- In testimony whereof We affix oursgnatures in presence of two witnesses.

J. GOODMAN. HENRY M. GOODMAN.

i Witnesses:

TOM B. MEGLEMRY, J. SHORT. 

